Transcript - Cleveland Clinic EMS Education

12 Lead ECGs:
Ischemia, Injury &
Infarction
Thomas Beers, EMS Coordinator
Cleveland Clinic Health System
Objectives
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Definitions
Why 12 Leads?
Injury/Infarct Recognition
Leads and Views
Reciprocal Changes
Evolution of an AMI
Practice Cases
Where do they go?
Local EMS Unit
CCF ER
Cardiologists
Blackberry
EMS Office
Why 12 Lead ECGs?
• Demonstrated Advantages
– Rapid Identification of Infarction/Injury
• diagnosis made sooner in many cases
• Administration of critical & time sensitive medications
– Decreased Time to Cath Lab Treatment
• speeds preparation of & time to cath lab
• Increased Index of Suspicion
– It is what we can do BEST!
Why 12 Lead ECGs?
• Perceived Disadvantages
– No clinical advantage to patient & “our
transport times are short”
• demonstrated decrease in time to treatment (D2B)
• compare to early notification for trauma patients
– Increased time spent on scene
• demonstrated an avg. <4 min increase
– Cost
• equipment & training (How many of you have paid
for a LP 12 or 15?)
Critical Concepts in ACS
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Pain is Injury
Pain-Free is the Goal
Time is Muscle
Door to Cath Lab Time is the issue
Acquisition & Transmission
• ECG quality begins with skin
preparation and electrodes
– Hair removal
– Skin preparation
– Age & Quality of Electrodes &
Cables
– Electrode Placement
Acquisition & Transmission
• Hair Removal
– Clipper over razor
• Lessens risk of cuts
• Quicker
• Disposable blade clippers available
– Most EMS systems use razors
Acquisition &
Transmission
Acquisition & Transmission
•Skin Preparation
– Helps obtain a strong signal
– When measured from skin, heart’s
electrical signal about 0.0001 - 0.003
volts
– Skin oils reduce adhesion of electrode
and hinder penetration of electrode gel
– Dead, dried skin cells do not conduct
well
Acquisition & Transmission
Rubbing skin
with a gauze
pad can
reduce skin
oil
and remove
some of dead
skin cells
Acquisition & Transmission
• Other causes of artifact
– Patient movement
– Cable movement
– Vehicle movement
Acquisition & Transmission
• Patient Movement
– Make patient as comfortable as possible
• Supine preferred
– Look for subtle movement
• toe tapping, shivering
– Look for muscle tension
• hand grasping rail, head raised to “watch”
Acquisition & Transmission
• Cable Movement
– Enough “slack” in cables to avoid tugging
on the electrodes
– Many cables have clip that can attach to
patient’s clothes or bed sheet
Acquisition & Transmission
• Vehicle Movement
– Acquisition in a moving vehicle is NOT
recommended
• May or may not be successful
– Tips
• Pull ambulance over for 10-20 seconds during
acquisition
• Acquire ECG while stopped at traffic light
Acquisition & Transmission
• Things to look for
– Little or no artifact
– Steady isoelectric line
What it should look like…
What it should NOT look like
Acquisition & Transmission
• ECG Accuracy depends upon
– Lead placement
– Frequency response
– Calibration
– Paper speed
Limb Lead Placement
Traditional
Placement
Avoid
placing on
the trunk!!!
Acceptable
Placement
Chest Lead Placement
• V1: fourth intercostal space
to right of sternum
• V2: fourth intercostal space
to left of sternum
• V3: directly between leads
V2 and V4
• V4: fifth intercostal space at
left midclavicular line
• V5: level with V4 at left
anterior axillary line
• V6: level with V5 at left
midaxillary line
Anatomy Revisited
• RCA
– right ventricle
– inferior wall of LV
– posterior wall of LV
(75%)
– SA Node (60%)
– AV Node (>80%)
• LCA
–
–
–
–
septal wall of LV
anterior wall of LV
lateral wall of LV
posterior wall of LV
(10%)
The Three I’s
• Ischemia
– lack of oxygenation
– ST segment depression or T wave inversion
• Injury
– prolonged ischemia
– ST segment elevation
• Infarct
– death of tissue
– may or may not show a Q wave
Injury/Infarct Recognition
Well Perfused Myocardium
Epicardial Coronary Artery
Septum
Lateral Wall of LV
Positive Electrode
Interior Wall of LV
Injury/Infarct Recognition
Normal ECG
Injury/Infarct Recognition
Ischemia
Epicardial Coronary Artery
Septum
Left
Ventricular
Cavity
Lateral Wall of LV
Positive Electrode
Interior Wall of LV
Injury/Infarct Recognition
• Ischemia
– Inadequate oxygen to tissue
– Represented by ST depression or T
inversion
– May or may not result in infarct or
Q waves
Injury/Infarct Recognition
ST Segment Depression & Inversion
Injury/Infarct Recognition
Injury
Thrombus
Ischemia
Injury/Infarct Recognition
• Injury
– Prolonged ischemia
– Represented by ST elevation
• referred to as an “injury pattern”
– Usually results in infarct
• may or may not develop Q wave
Injury/Infarct Recognition
ST Segment Elevation
Injury/Infarct Recognition
Infarct
Infarcted Area
Electrically Silent
Depolarization
Injury/Infarct Recognition
• Infarct
– Death of tissue
– Represented by Q wave
– Not all infarcts develop Q waves
Injury/Infarct Recognition
Q Waves
Injury/Infarct Recognition
• What to Look
for:
– ST segment
elevation
– Present in two
or more
anatomically
contiguous
leads
Lead “Views”
Lead Groups
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Limb Leads
Chest Leads
LIILI-SSAALL
Which coronary arteries are most
likely associated with each group of
contiguous leads?
I Lateral
aVR
II Inferior
aVL Lateral
III Inferior
aVF Inferior
V1 Septal
V4 Anterior
V2 Septal
V5 Lateral
V3 Anterior
V6 Lateral
Lateral Wall
• I and aVL
– View from Left Arm 
– lateral wall of left ventricle
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Lateral Wall
• V5 and V6
– Left lateral chest
– lateral wall of left ventricle
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Lateral Wall
• I, aVL, V5, V6
– ST elevation  suspect
lateral wall injury
Lateral Wall
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Inferior Wall
• II, III, aVF
– View from Left Leg 
– inferior wall of left ventricle
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Inferior Wall
• Posterior View
– portion resting on diaphragm
– ST elevation  suspect inferior
injury
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Inferior Wall
Septal Wall
• V1, V2
– Along sternal borders
– Look through right ventricle &
see septal wall
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Septal
• V1, V2
– septum is left
ventricular tissue
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Anterior Wall
• V3, V4
– Left anterior chest
–  electrode on anterior chest
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Anterior Wall
• V3, V4
– ST segment
elevation 
suspect anterior
wall injury
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Reciprocal Changes
Reciprocal Changes
II, III, aVF
I, aVL, V leads
Reciprocal Changes
• Reciprocal changes
– Not necessary to presume infarction
– Strong confirming evidence when
present
– Not all AMIs result in reciprocal
changes
Reciprocal Changes: Practice
12-Lead ECG
• AMI recognition
– Two things to know
• What to look for
• Where you are looking
L
I
L
I
I
S
A
S
L
A
L
AMI Recognition
• What to look for
– ST segment elevation
• One millimeter or more (one small box)
• Present in two anatomically contiguous
leads
L
I
L
I
I
S
A
S
L
A
L
Practice Case “Tools”
• Must take into Account
– Story
– Risk factors
– ECG
– Treatment
Injury/Infarct Recognition:
Practice
Practice
Practice
TOMBSTONES
Practice Case 1
• 48 year old male
– Dull central CP 2/10, began at rest
• Pale and wet
• Overweight, smoker
• Vital signs: RR 18, P 80, BP
180/110, Sa02 94% on room air
Practice Case 1
Practice Case 2
• 68 year old female
– Sudden onset of anxiety and restlessness,
– States she “can’t catch her breath”
– Denies chest pain or other discomfort
• History of IDDM and hypertension
• RR 22, P 40, BP 190/90, Sa02 88%
on NC at 4 lpm
Practice Case 2
BUT WAIT!!!!!!!!!!!!!!
STEMI Mimics
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LBBB
RBBB
Pericarditis
LVH
LBBB vs. RBBB
Pericarditis
LVH
LVH
AMI Recognition
A normal 12-lead ECG DOES NOT
mean the patient is not having acute
ischemia, injury or infarction!!!
The Future of STEMI Care
• E2B
- Integration of EMS, ED, and
Cardiology
- full disclosure of pt outcomes (QI)
- seamless transitions of pt. care
Thank You!
Questions, Comments?
www.clevelandclinicEMS.com